[TexasGator]

coup de grâce
NOUN
a final blow or shot given to kill a wounded person or animal:

[PetroniusMaximus]

This just after they threatened to kill his kid.

[Steve Van Doorn]

said, "coup(e) de grâce
NOUN
a final blow or shot given to kill a wounded person or animal:

He was referencing a Coup d'état mixed with Coup de grâce

ClearCase_guy
It’s a bit like Q — but harder for people to laugh off as a LARP.

One thing Q isn't or wasn't is a complex LARP. It was clearly done by highly intelligent people that had inside information. Which used psychological techniques.
If they're black hats, white or something else is open for debate.
If they're pranksters they would have to be black hats with the intent to divert which I wouldn't disagree with you.